Sona Sitri is a High-Class Devil from the Sitri Clan and a third-year student at Kuoh Academy. She is the President of Kuoh Academy's Student Council and a childhood friend and rival of Rias Gremory. Like Rias, she is also the heiress to her clan. Her alias at Kuoh Academy is Souna Shitori, and she is the third most popular girl at the Academy, behind Rias and Akeno.

Sona is shown to be a very strict and intelligent person. Whether it is a matter of the Student Council or the Sitri Clan, she does not take anything lightly. Sona is very dedicated to her dream of opening a Rating Game School that is open to all regardless of their status, even going to a human school to learn of their system.

Like Rias, Sona became the heiress of her clan after her sister, Serafall, became a Satan, which resulted in the latter losing the right to inherit the clan. She also had a fiancé, but she broke off their engagement by beating him in a game of chess, claiming that she will not marry someone that is not smarter than her. She entered Kuoh Academy at the same time with Rias, Akeno, Tsubaki, and Kiyome, and later became the Vice-President of the Student Council during her second year.

She first appears in Volume 3 along with her peerage, the members of the Student Council, for a meeting with the Occult Research Club to introduce their new members. She then reprimands her new Pawn, Genshirou Saji, for making fun of Issei Hyoudou and nearly challenging him to a fight. She and Rias later found out that Saji and Rias' servants formed an alliance with Xenovia and Irina Shidou to destroy the Excalibur fragments. She then punishes Saji (with 1000 spankings) for acting on his own, and without her permission. When Kokabiel decided to attack Kuoh Academy, Sona and her peerage assisted in forming a barrier to surround the school while maintaining it from outside.

In Volume 4, during the class observation day, Sona's sister came to her school, much to her shock and chagrin. She eventually ran away due to the embarrassment caused by her sister. She was also present during the conference of the Three Factions, and was frozen by Gasper's time freezing ability when the Khaos Brigade attacked.

In Volume 5, Sona returns to the Underworld, where she was one of the six chosen young Devils along with Rias, Sairaorg Bael, Diodora Astaroth, Seekvaira Agares, and Zephyrdor Glasya-Labolas. During the opening ceremony, Sona states her dream of opening a school for Rating Game for all Devils regardless of their classes which was made fun of by the elder Devils. She later had a Rating Game against Rias, creating a strategy where she used a hologram of herself as bait while having her two Bishops create a barrier to hide her presence while waiting for the Gremory Team to self-destruct. She almost won the match until Issei, before retiring, reveals his new move, Bilingual, to talk with her spirit's breasts to discover her strategy. She then goes to fight Rias in a one-on-one battle, but lost to the latter due to resignation.

She faces Seekvaira Agares in a Rating Game (Scramble Flag) in Volume 10, which her team won despite the fact that Saji went berserk near the end of the match. Although the said Rating Game did not get as much of an audience as the Gremory-Bael match, the Sitri-Agares match was highly acclaimed by experts.

In Volume 11, Sona congratulates Issei on his recommendation of promotion for Middle-Class Devil, and after hearing that Issei confessed to Rias, she reveals that she wishes to give Rias as strong support as possible. She also suggested to Issei that he call her by her first name whenever they were alone since Issei is already Rias' boyfriend which makes him Sona's friend too, but Issei couldn't, and she guesses that Issei receives dissatisfaction from Rias and Akeno regarding how he calls them at private times. When Issei questions how she found out, she gave a small laugh, stating that gentlemen who could separate the way they talk to ladies are even more wonderful. She also reveals that she is envious of Rias and Issei's relationship, and starts to think about getting a boyfriend as well. When Issei suggests Saji, Sona rejects the idea since she sees Saji as a little brother, and also because some of the members of her peerage are attracted to Saji. Later on, Rias also revealed that Sona had found candidates for her additional Rook and Knight.

In Volume 12, Sona and Saji went to the Gremory Palace to check on Rias and the Gremory Team after hearing about Issei's "death", telling Saji not to get too emotional as she too would be troubled if Saji died and left after telling Yuuto that she called the most suitable person to cheer Rias up. Sona and her peerage later faced off against Heracles and Jeanne from the Hero Faction, losing to them after the two of them used the children of the Underworld as hostages to gain an advantage over the Sitri Group. After Gasper defeats Georg, Sona tells Rias and the Gremory Team that they might face future problems with Magicians.

In Volume 14, she and her peerage helps the Occult Research Club in rescuing their first year members, forming various strategies for the two teams, allowing them to defeat the strayed Magicians with ease. Later, she and Saji went along with the Occult Research Club by Euclid Lucifuge and watched the fight between Issei and Grendel.

In Volume 15, Sona, along with Bennia, visited the Hyoudou Residence to discuss what the Sitri and Gremory groups would do while Rias, Yuuto and Azazel are in Romania. They did their discussion in the underground pool when Kuroka and Le Fay arrived and was shocked when Kuroka mentioned that they fought the Evil Dragon, Aži Dahāka. Sona asked Le Fay if she can get additional information about the fight in which Le Fay complied to. When Griselda Quarta, Dulio Gesualdo, and Tobio Ikuse later arrived and told them that the two Longinus possessors will help train the group, Sona asked if Saji can join as well to help him achieve Balance Breaker in which they agreed to.

In Volume 16, Sona instructed Bennia and Loup Garou to go to Romania with the ORC members. She, along with the Student Council, later participated in the meeting for the formation of D×D.

Sona supervised the experience day of the school she built in Volume 17. When Qlippoth, Sona directed the fight and was partnered with Gasper.

Sona participated in the fight against the exorcists that rebelled against the Church in Volume 19. Once again, she directed the fight against the group of exorcists led by Ewald Cristaldi.

Water-Based Magic: As a member of the Sitri Clan, Sona specializes in water manipulation, with her control over her techniques surpassing that of Rias, during her fight against Rias where she easily controlled large volume of water. She has also demonstrated the ability to change the form various creatures out of water, such as multiple hawks that flew in the air, serpents that slithered on the ground, valiant lions, wolves that herded together, and several large Dragons.

Master Tactician: Sona's true strength is her unparalleled skill in strategy making, which allows her to command her peerage to great effect. Sona has proven that she is an excellent strategist twice, the first during the Rating Game against the Gremory Team which allowed her team to battle on level with the Gremory Team despite the difference in strength. The second was when the Stray Magicians and Magician from Khaos Brigade attacked the Sitri and Gremory Team, and she easily formulated multiple strategies to counter them while devising powerful combination techniques.

Sona's body measurements are B77-W57-H83 cm. (B30-W22-H33 in.) and her height is 166 cm. (5 feet 5 inches), according to the visual book with her data.

Sona's alias, "Souna Shitori", has the same Romaji as her real name, albeit with minor changes in the stresses in syllables (for example, ソーナ (Sōna) being changed to そうな (Souna) and シトリー (Shitorī) being changed to しとり (Shitori))

Sona and Rias share many similarities:

They are both heiresses to their respective clans.

Both are presidents of their respective clubs.

Their older siblings are both Satans.

They were both previously engaged at one point (Rias during the series, Sona prior to it).

Their respective pawns are in love with them as well as dragon-type sacred gear possessors.

Sona is known as one of the "Rookies Four" along with Rias, Sairaorg, and Seekvaira.